An Arab selective gradient in the distribution of factor V G1691A (Leiden), prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T

Association between Toll-like receptor 2 rs4696483 and rs1898830 polymorphisms and the risk of triple-negative breast cancer

PURPOSE

Breast cancer (BC) is heterogeneous in clinical manifestation, of which the triple-negative (TNBC) subtype is the most aggressive. This study examines the associations between Toll-Like Receptor (TLR)-2 polymorphisms and the susceptibility to BC and TNBC.

METHODS

Genotyping of TLR-2 rs1898830 and rs4696483 polymorphisms was done by real-time PCR in 488 women with BC (130 TNBC, 358 non-TNBC) and 476 cancer-free control women.

RESULTS

The minor allele frequency (MAF) of rs4696483 was significantly lower in BC cases compared to controls, and significantly lower frequencies of rs4696483 C/T and higher frequencies of rs1898830 G/G genotypes were seen in BC cases. Significantly higher MAF of rs4696483 and higher C/T and T/T rs4696483 genotypes frequencies were seen in TNBC than in non-TNBC cases. Considering the prevalent AC haplotype as a reference, 2-locus TLR-2 haplotype analysis did not identify any 2-locus TLR-2 haplotype associated with an altered risk of BC or TNBC. Positive associations of rs1898830 and rs4966483 were seen with the histological type in TNBC and negatively with distant metastasis and HR status in TNBC and non-TNBC rs1898830 carriers. In addition, rs4696483 was positively correlated with hormonotherapy and surgery in non-TNBC cases, while rs1898830 was negatively associated with hormonotherapy. Furthermore, rs1898830 was negatively and positively correlated with BMI in TNBC and TNBC cases, respectively, but positively with Ki-67 status.

CONCLUSIONS

Our study highlights the association between TLR-2 genetic polymorphisms and BC and TNBC susceptibility, suggesting these variants' diagnostic/prognostic capacity in BC patients and patient subgroups.

Involvement of MTHFR rs1801133 in the Susceptibility of Acute Lymphoblastic Leukemia: A Preliminary Study

BACKGROUND

Acute lymphoblastic leukemia (ALL), a common blood cancer, is characterized by the interaction between genetic and environmental factors. Several variants of the Methylenetetrahydrofolate reductase (MTHFR), mainly the C677T (rs1801133), may affect susceptibility to ALL.

AIM OF THE STUDY

The authors conducted this case-control study to evaluate the relationship between this variant of the MTHFR gene and the risk of ALL.

MATERIALS AND METHODS

Forty-one patients with ALL and 35 non-ALL controls recruited in this study were genotyped utilizing polymerase chain reaction-restriction fragment length polymorphism methodology.

RESULTS

The MTHFR 677CT genotype was significantly more frequently found in patients with ALL having a 2-fold increase in risk (P <0.01).

CONCLUSION

Our results suggest that rs1801133 of MTHFR is a predictive risk marker to ALL in Tunisian ALL.

Distribution of MTHFR C677T Gene Polymorphism in Healthy North Indian Population and an Updated Meta-analysis

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme of folate pathway. Several polymorphisms were reported in MTHFR gene but C677T polymorphism is most studied and it has been reported to be risk factor for several diseases/disorders. The present study was designed to explore the frequency of MTHFR C677T polymorphism in North Indian healthy population. In addition to this a meta-analysis of published articles was also performed to estimate the global prevalence of MTHFR C677T polymorphism. A total of 1000 unrelated healthy subjects were selected for MTHFR C677T polymorphism analysis. Different databases were searched for eligible articles. Prevalence proportion with 95 % CI was used to determine global prevalence of T allele and TT genotype. Meta-analysis was performed by Open meta-analyst. In 1000 blood samples analyzed, the frequency of T allele and TT genotype was 11 and 1 % respectively. Results of the meta-analysis showed that the global prevalence of T allele and TT genotype were 24.0 % (95 % CI 21.7-26.5) and 7.7 % (95 % CI 6.5-8.9) respectively. In sub-group meta-analysis, the lowest frequency of T allele was found in Africans (10.3 %; 95 % CI 3.8-16.8), and highest in Europeans (34.1 %; 95 % CI 31.9-36.3). The frequency of T allele in the North India is 11 %. The results of the meta-analysis showed that the frequency of the T allele and the TT genotype of C677T is highest in the Caucasian population.

Genetic Risk Factors of Venous Thromboembolism in the East Algerian Population

Many genetic risk factors have been identified for causing venous thromboembolism (VTE). Most of them affect the function of natural anticoagulant pathways, particularly the protein C system, although recent studies suggest a role of components of the hematopoietic pathway in the etiology of venous thrombosis. In this case–control study, we aimed to determine the frequency of prothrombin G20210A and factor V Leiden (FVL) G1691A polymorphisms and protein C, protein S, and antithrombin III deficiencies in the East Algerian population and to investigate whether these genetic factors are associated with VTE. On the other hand, our study tends to evaluate the status of JAK2V617F and calreticulin (CALR) mutations among these cases. The participants consisted of 121 cases with VTE and 146 healthy controls. Polymorphisms of FVL G1691A and prothrombin G20210A were genotyped by polymerase chain reaction (PCR) restriction fragment length polymorphism. JAK2-V617F and calreticulin mutations were analyzed by quantitative PCR and PCR followed by capillary electrophoresis sequencing, respectively. Protein C, protein S, and antithrombin levels were determined and then hereditary deficiencies were identified. Of all cases and controls, none was a carrier of the antithrombin III deficiency, prothrombin gene G20210A, and CALR mutations. Only 1 case reported having a positive JAK2 mutation (mutant allele burden was 15%). The FVL mutation (GA/AA) was found in 14 (11.6%) cases and 2 (1.4%) controls and it was significantly different between both the groups ( P = .001). Deficiencies of protein S and protein C were detected in 17 (18.8%) cases. The univariate analysis resulted in a significant impact of FVL (odds ratio [OR] = 9.4, 95% confidence interval [CI] = 2.1-42.3; P = .003) and of protein S deficiency (OR = 16.9, 95% CI =2.1-132.8, P = .007) on the VTE status. Both factors stayed significant after adjustment for sex and age. The OR of the protein C deficiency was slightly elevated (OR = 6.4, 95% CI = 0.7-55.5), but it did not reach the level of statistical significance ( P = .091), and it was therefore not considered as a risk factor. In conclusion, coagulant factor V gene G1691A mutation and protein S deficiency constitute important genetic risk factors in patients with VTE in Eastern Algeria. The somatic mutation of JAK2 V617F and CALR mutations are less frequent causes of VTE, thus routine testing for these mutations is not recommended.

Ethnic diversity in the genetics of venous thromboembolism

Genetic susceptibility is considered as a crucial factor for the development of venous thromboembolism (VTE). Epidemiologic and genetic studies have revealed clear disparities in the incidence of VTE and the distribution of genetic factors for VTE in populations stratified by ethnicity worldwide. While gain-of-function polymorphisms in the procoagulant genes are common inherited factors in European-origin populations, the most prevalent molecular basis for venous thrombosis in Asians is confirmed to be dysfunctional variants in the anticoagulant genes. With the breakthrough of genomic technologies, a set of novel common alleles and rare mutations associated with VTE have also been identified, in different ethnic groups. Several putative pathways contributing to the pathogenesis of thrombophilia in populations of African-ancestry are largely unknown, as current knowledge of hereditary and acquired risk factors do not fully explain the highest risk of VTE in Black groups. In-depth studies across diverse ethnic populations are needed to unravel the whole genetics of VTE, which will help developing individual risk prediction models and strategies to minimise VTE in all populations.

Thrombophilic risk factors in different types of retinal vein occlusion in Tunisian patients

BACKGROUND

Retinal vein occlusion (RVO) is the second most common cause of vision loss because of retinal vascular disease. There are 2 types of RVO: branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO). The pathogenesis of RVO is multifactorial. The role of factor V Leiden (FVL) and prothrombin mutations was examined in patients with CRVO and BRVO.

METHODS

FVL and prothrombin were investigated by extracting DNA of 88 patients with RVO. Sixteen of the patients were diagnosed with CRVO, 4 with hemispheric retinal vein occlusion, and 68 with BRVO. The genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Significant differences were found in the frequencies of the genotypes for both the FVL (G1691A) (P<10(-3), odds ratio [OR]=17.4, confidence interval [CI]=6.20-59) and prothrombin (G20210A) (P=.007, OR=5.11, CI=1.30-29) polymorphisms between RVO patients and healthy controls. Additionally, the frequency of the GA genotype for the G1691A polymorphism was significantly higher among the patients in a subset of BRVO compared with controls (P<10(-3), OR=21.4, CI=7.34-74.2). However, no statistically significant differences were found in the frequencies of the prothrombin G20210A polymorphism between the BRVO group and healthy controls (P=.09, OR=3.13, CI=64-19.9). The frequency of both G1691A and G20210A genotypes among the patients of a CRVO subgroup was significantly higher compared with controls (P<10(-3), OR=11.4, CI=2.94-44.2; P=.007, OR=10.8, CI=2.15-54.1, respectively), suggesting an association between these polymorphisms and CRVO.

CONCLUSIONS

Large study would be required to understand completely the contribution of these markers in the risk of all types of RVO.

Epidemiology of Prothrombin G20210A Mutation in the Mediterranean Region

There are many genetic and acquired risk factors that are known to cause venous thromboembolic disorders (VTE). One of these is the Prothrombin G20210A mutation, which has been identified in 1996. Prothrombin G20210A mutation causes higher levels of the clotting factor prothrombin in the blood of carriers, which creates a higher tendency towards blood clotting (hypercoagulability), and therefore the carriers become at higher risk of developing VTE. High prevalence of Prothrombin G20210A mutation was reported in Caucasian populations, but the prevalence was almost absent in non-Caucasians. That was most obvious in countries of South Europe and the Mediterranean region. This review article discusses Prothrombin G20210A mutation, how it causes VTE, the origin of the mutation, and its distribution worldwide with special concentration on the Mediterranean area.

Combined effect of NAT2, MTR and MTHFR genotypes and tobacco on bladder cancer susceptibility in Tunisian population

BACKGROUND

Cigarette smoking is the predominant risk factor for bladder cancer. This risk may be modified by polymorphisms in carcinogens metabolism genes; including those involving the N-acetyl transferase 2 (NAT2) which have been correlated with decreased enzyme activities. Moreover, folate insufficiency can induces carcinogenesis by decreasing DNA methylation. Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MTR) are enzymes that play central roles in the folate metabolic pathway. The MTHFR 677*T and MTR 2756*G variants are associated with decreased enzyme activity.

METHODS

In this work, we have conducted a case-control study in order to assess the combined effect of tobacco, slow NAT2 variants, MTHFR 677*T and MTR 2756*G alleles on bladder cancer development in North Tunisia.

RESULTS

For MTR A2756G, alleles and genotypic distributions differed significantly between cases and controls (p = 0.00009, OR = 3.27, CI 95% 1.76-6.12). While, in non-smokers patients the slow NAT2 did not appear to influence bladder cancer susceptibility; our results suggested that it might act with an additive contribution with tobacco as well as with that determined by MTR 2756 AG or 2756 GG genotypes (p = 0.0008). Identical cumulative effect was detected for slow NAT2 and MTHFR 677*T variant (p = 0.0003; OR = 36.6; CI 95% 3.4-935.3).

CONCLUSION

The strongest result obtained by this study was for an additive effect between smoking status, slow NAT2 variants, MTR 2756*G and MTHFR 677*T alleles, in affecting bladder cancer risk.

The Prevalence of Methylenetetrahydrofolate Reductase 677 C-T, Factor V 1691 G-A, and Prothrombin 20210 G-A Mutations in Healthy Populations in Sétif, Algeria

The polymorphic mutation 677 C-T in the methylenetetrahydrofolate reductase (MTHFR) gene presents a heterogeneous worldwide distribution and is associated with different disorders such as cardiovascular disease. Its frequency shows great ethnic and geographic variations. The aim of this work is to determine the frequency of MTHFR 677 C-T and coexistence of MTHFR 677 C-T with 2 other common, hereditary thrombophilia causes—namely, factor V 1691 G-A and prothrombin (PT) 20210 G-A mutation—in the Sétif region of Algeria. The study involved 147 apparently healthy participants (82 men and 65 women). Genotyping was carried out by a real-time polymerase chain reaction. The MTHFR 677T carrier frequency was found to be 54.4% (80/147); 59 individuals were heterozygous (40.1%), and 21 were homozygous (14.3%). The frequency of MTHFR 677T was found to be 34.3%. Among the 147 individuals, 3 (2.0%) had factor V Leiden, and 5 (3.4%) had PT 20210 A mutation. Of the 80 participants with MTHFR 677T mutation, 2 had heterozygote factor V 1691 G-A gene mutation, and 4 had heterozygote PT 20210 G-A gene mutation. The results showed that MTHFR 677T prevalence is quite high: an allelic frequency of 34.3% with a genotype frequency of 14.3%. Factor V 1691 G-A and PT 20210 G-A gene mutations are rare in the healthy population of the Sétif region of Algeria.

Thrombophilic polymorphisms in Israel

Three thrombophilic polymorphisms, FV G1691A, FII G20210A and MTHFR C677T were investigated in Israeli populations by FRET, (fluorescence resonance energy transfer) real-time PCR. We observe extensive variability in the frequencies of each of the polymorphisms, as has been observed in the study of other polymorphisms in these populations. Very high allele frequencies for FV G1691A (the highest 0.087 in Turkish and Greek Jews) and FII G20210A (the highest 0.061 in Georgian Jews) in some of the Israeli populations justify a clinical investigation to assess their risk for venous thrombosis. Principal Coordinates Analysis demonstrates that the Jewish populations are interspersed among the non-Jewish populations. The resemblance of some Jewish populations to certain non-Jewish populations coincides with findings based on classical markers.

Methylenetetrahydrofolate reductase and methionine synthase polymorphisms and risk of bladder cancer in a Tunisian population

Folate insufficiency can induce carcinogenesis by decreasing DNA methylation. It is well known that DNA hypomethylation is a common feature in a number of cancers. Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MS) are enzymes that play central roles in the folate metabolic pathway. Two common polymorphisms in the MTHFR gene (C677T and A1298C) and one in the MS gene (A2756G) are associated with decreased enzymatic activity. In this work, we have conducted a case-control study to assess the role of these three polymorphisms in bladder cancer development in North Tunisia. For MS A2756G, gene and genotypic distributions differed significantly between cases and controls. Furthermore, individuals carrying at least one copy of the variant allele presented a 2.33 times increased risk of developing bladder cancer than their control group [P = 0.001, odds ratio (OR) = 2.33; 95% confidence interval (CI) 1.34-4.06]. Statistically significant odds ratios were also found in patients heterozygous for MTHFR A1298C, who have a 1.8-fold higher risk of developing bladder cancer (P = 0.03, OR = 1.86; CI 95% 1.04-3.33). While the isolated polymorphism C677T did not appear to influence bladder cancer susceptibility, results suggest that it might act with an additive contribution determined by variation at MTHFR A1298C. Identical cumulative effect was detected for the MTHFR A1298C and MS 2756 genotypes. Patients harboring at least one mutant allele for each of the three positions analyzed showed a 4.76-fold increased risk of developing bladder cancer in comparison to their reference group (P = 0.02, OR = 4.76; CI 95% 1.26-17.98).

MTHFR C677T and A1298C gene polymorphisms and hyperhomocysteinemia as risk factors of diabetic nephropathy in type 2 diabetes patients

Point mutations in methylenetetrahydrofolate reductase (MTHFR) and hyperhomocysteinemia were implicated in the pathogenesis of diabetic nephropathy (DN) in many ethnic groups. This study addressed the association of C677T and A1298C single nucleotide polymorphisms (SNPs) of MTHFR gene with DN in Tunisian type 2 diabetes (T2DM) patients. Study subjects comprised 93 DN patients, 267 patients with normoalbuminuria, and 400 control subjects. C677T and A1298C genotypes were determined by PCR-RFLP analysis, and homocysteine levels were measured by ELISA. A1298C and C677T were highly prevalent among T2DM patients, with allele frequencies of 0.26 and 0.36, respectively. Higher mutant 677T allele and 677C/T and 677T/T genotypes of C677T SNP, but not A1298C SNP, together with 677C/1298A, 677C/1298C, and 677T/1298A haplotypes were seen in DN patients compared to normoalbuminuric patients, (p<0.001). Plasma homocysteine was positively associated with MTHFR 677T/T genotype among the three groups, and was significantly elevated in double heterozygous DN patients but not in normoalbuminuric patients or controls. Logistic regression analysis with DN as dependent variable showed that homocysteine (OR, 1.153) and MTHFR 677T/T (OR, 9.799) were the only variables associated with DN, after adjusting for possible confounding variables. C677T, but not A1298C, SNP, is a risk factor for DN, presumably acting by elevating homocysteine levels.

Magnifying endoscopic observation of the gastric mucosa, particularly in patients with atrophic gastritis

The gastric mucosal surface was observed using the magnifying fibergastroscope (FGS-ML), and the fine gastric mucosal patterns, which were even smaller than one unit of gastric area, were examined at a magnification of about 30. For simplicification, we classified these patterns by magnifying endoscopy in the following ways; FP, FIP, FSP, SP and MP, modifying Yoshii's classification under the dissecting microscope. The FIP, which was found to have round and long elliptical gastric pits, is a new addition to our endoscopic classification. The relationship between the FIP and the intermediate zone was evaluated by superficial and histological studies of surgical and biopsy specimens. The width of the band of FIP seems to be related to the severity of atrophic gastritis. Also, the transformation of FP to FIP was assessed by comparing specimens taken from the resected and residual parts of the stomach, respectively. Moreover, it appears that severe gastritis occurs in the gastric mucosa which shows a FIP. Therefore, we consider that the FIP indicates the position of the atrophic border.